In general, the present disclosure relates to an imaging device and an imaging apparatus. More particularly, the present disclosure relates to an imaging device capable of suppressing local non-uniformities of the imaging characteristic of the imaging device, and an imaging apparatus employing the device.
In recent years, improvements of the manufacturing technologies of semiconductors allow progress to be made in semiconductor-device miniaturization and the sizes of semiconductor-device chips to be increased. In addition, the sizes of masked circuits are also raised as well. For example, the number of pixels included in an imaging device masked in one chip increases. A typical example of such an imaging device is a CMOS (Complementary Metal Oxide Semiconductor) image sensor.
In a CMOS image sensor having a large chip size as is the case with a 35 mm-size sensor for example, due to apparatus restrictions, the entire chip cannot be exposed at one time. If infinitesimal devices should be created all over the large area of the CMOS image sensor in a device creation process, conceivably, the area is to be divided into a plurality of sub-areas in every of which the devices can be created once. Then, the sub-areas are joined to each other in order to create the large area of the CMOS image sensor. This method for creating such a CMOS image sensor having a large area is referred to as an area division/concatenation method. For example, Japanese Patent Laid-open No. 2005-223707 proposes the use of a technology referred to as a division exposure technique for creating a large solid-state imaging device.
As described above, however, if the division exposure technique is adopted, the adjustment shift of a portion on the right-hand side of an exposure boundary line is different from the adjustment shift of a portion on the left-hand side of the exposure boundary line. As a result, the characteristic of the portion on the right-hand side of the exposure boundary line is also different from the characteristic of the portion on the left-hand side of the exposure boundary line. If the difference in characteristic changes gradually, no big problem is raised. If left and right exposure processes are carried out, however, this boundary is created on a straight line, resulting in a distinct difference in characteristic. Thus, a clear difference in characteristic between the right and left portions on both the sides of the boundary line is noticeably observed.
In the case of a solid-state imaging device for example, this boundary is created on a straight line, giving rise to a clear difference in characteristic. In this case, an output difference between the right and left portions on both the sides of the boundary line is visibly recognized as a luminance line or a black line so that the boundary becomes striking.
In order to solve the problem described above, there has been devised a method disclosed in documents such as Japanese Patent Laid-open No. 2010-141093. In accordance with this method, a device portion simultaneously created in a specific process is mixed with a device portion simultaneously created in another process. In the specific process, exposure processing and ion injection are carried out for a specific sub-area whereas, in the other process, the exposure processing and the ion injection are carried out for the other sub-area.